From Gogeometry
Using :
- Define R radius of circle O and r radius of circle Q
- By construction and symmetry
- A, O, Q, D are collinear
- DE=DF, AE=AF
- AD angle bisector of ∠BAC
- D symmetric of A by O => ED=EA=FD=FA : AEDF is a diamond
=>O middle of EF and EF ⊥ AD - ΔABC equilateral and AD angle bisector of BAC => ∠CAD=Π/6
- ∠FAO=Π/6 and ∠AOF=Π/2 => ∠AFO=Π/3
- ∠AFO intercepts arc FE of circle Q => ∠EDF=Π/3
- ∠EDF=Π/3 and DE=DF => ΔEDF is equilateral
- QD=r, OD=R, ΔEDF is equilateral
=> QD=2OD/3 => r=2R/3 and R/r=3/2 - S=[Circle O]-[Circle Q], S1=[Circle Q]=> S/S1=[Circle O]/[Circle Q]-1
=> S/S1=(R/r)^2-1=9/4-1
Therefore S/S1=5/4